Molding apparatus

ABSTRACT

Apparatus for pressure molding a shaped article such as a food patty from moldable food material comprising a supply means such as a hopper for the material, a pressure chamber, a movable ram in the pressure chamber to pressurize the material therein, a receiver chamber such as a cylinder communicating with the pressure chamber to receive the pressurized material, a wall member such as a piston movable in the receiver chamber displaced by the force of the material entering thereinto, a mold having a mold opening adapted to register with the material in the receiver chamber, and mold filling means for forcibly moving this wall member to apply pressure to the material in the receiver chamber thereby forcing the moldable material into the mold opening.

This is a continuation of application Ser. No. 619,848 filed Oct. 6,1975, and now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to an improved apparatus for pressure molding ashaped article such as a hamburger patty from a tissue containing foodmaterial such as ground raw beef that is subject to shrinkage duringcooking. The apparatus provides a supply of the material, a receiverchamber such as a cylinder, a piston in the receiver chamber that ispositioned away from the mold plate to provide space for a preselectedamount of the material between the piston and the mold plate opening,mold filling means for forcibly moving the piston to apply pressure tothe material in the receiver chamber thereby filling the mold opening,the piston having a pressure applying end that is substantially flushwith the mold plate at the completion of the filling, means forthereafter moving the mold and thereby the mold opening to a positionwhere the mold opening is out of communication with the cylinder andwhere the article is ejected from the mold opening and means formaintaining the piston substantially flush with the mold during thismoving thereby maintaining the molding pressure on the material in themold opening. The result is a meat-to-meat shear between the material inthe mold opening and meat in the cylinder is avoided thereby preventingparallel alignment of the tissues and resulting nonuniform shrinkage.Because the apparatus of this invention avoids this parallel alignmentof the tissues the articles such as a food patty maintains its uniformshape during shrinkage caused by cooking.

The most pertinent prior art of which applicant is aware is R. G. HallU.S. Pat. No. 3,347,176 which also discloses a supply means, a cylinderand piston, a passage leading from the supply means to the cylinder andmeans for forcing the material from the cylinder into a mold plateopening by moving the piston toward the opening. However, the presentinvention has structure and advantages that are different from anythingdisclosed in this Hall patent as defined in the claims hereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a food material patty moldingapparatus embodying the invention.

FIG. 2 is a sectional view taken substantially along line 2--2 of FIG.1.

FIG. 3 is a view similar to FIG. 1 but showing the movable portions ofthe apparatus in positions opposite to those of FIG. 1.

FIG. 4 is a longitudinal fragmentary vertical sectional view through thetop portion of the apparatus of FIG. 1.

FIG. 5 is a horizontal sectional view taken substantially along line5--5 of FIG. 4 and illustrating primarily the mold plate and surroundingstructure.

FIG. 6 is a view similar to FIG. 4 but showing the parts of the upperportion of the apparatus in rearwardly retracted position from theforward position of FIG. 4.

FIG. 7. is a fragmentary vertical sectional view taken substantiallyalong line 7--7 of FIG. 6.

DESCRIPTION OF A PREFERRED EMBODIMENT

The molding apparatus 10 of the illustrated embodiment comprises ahopper 11 that comprises a supply means for the moldable material 12such as finely divided food material. At the bottom of the hopper thereis positioned a horizontal bottom plate 13 in which is located atransverse opening or slot 14 for projecting a preselected amount 15 ofmaterial 12 into a pressure chamber 16 that is defined by the spacebetween the bottom plate 13 and a parallel plate 17 spaced therebeneath.

Mounted for reciprocating forward and rearward movement between theplates 13 and 17 and thus in the pressure chamber 16 is a horizontal ram20 of vertically rectangular cross section. The horizontal extremes ofthe pressure chamber 16 are defined by a front wall 21 and a rear wall22 and forward of the front wall 21 is a receiver chamber verticalcylinder 23 that communicates with the pressure chamber 16 in the space25 thereof forwardly of the forwardmost position of the ram 20 asillustrated in FIG. 4.

As illustrated in FIGS. 4 and 5 this communication is by way of a bottomtransverse slot 25 in the plate 17 forwardly of the forwardmost positionof the ram 20 which is the position illustrated in FIG. 4 with this slot25 then communicating with an elongated passage 26 in an elongated moldplate 27 that is reciprocated between a forwardmost position of FIG. 4and a rearwardmost position of FIG. 6.

This fill passage 26 when the mold plate is in the retracted positioncommunicates with the bottom of the cylinder 23 in the space beneath avertically movable piston 30 therein. Thus the ram pressurized material31 which extends from the pressure chamber space 24 through the slot 25and the fill passage 26 is under sufficient pressure to raise thesubstantially freely movable piston 30 to the elevated position shown inFIG. 4. The amount of pressurized material 31 beneath the piston 30 ispreferably just sufficient to fill a mold opening 32 in the mold platewhen the piston 30 is forced to its lowermost position as shown in FIG.6 by means described hereinafter.

The piston 30 is basically a movable wall member that is movable in thecylinder that functions as a receiver chamber. Then, when the movablemold 27 has been moved to the filling position of FIG. 6 the piston isforcibly moved toward the mold opening to apply pressure to the materialin the receiver chamber thereby forcing the material into the moldopening.

In order to predetermine the amount of material received in the cylinder23 beneath the piston 30 the piston is provided with an upwardlyextending stem 33 that extends through the top 34 of the cylinder andthe stem 33 carries on its upper end a flat collar 35. This collar 35 incombination with an adjustable stop 36 preselects and determines theextent of upward movement of the piston 30 and thus the amount ofmaterial 31 received in the cylinder 23. This stop, in this embodiment,comprises an adjustable vertical screw having an adjusting knob 37 onits upper end and held in a vertical bracket 40 that is mounted on thetop 34 of the cylinder. This adjustable stop 36 provides for variableamounts of pressurized material 31 in the cylinder 23 depending upon thesize of the shaped article desired. Thus in the illustrated embodimentwhere the article is a flat patty 41 of food material such as groundmeat, fish and the like the adjustment will be of course to position thepiston 30 closer to the mold plate 27 for a 2 ounce patty, for example,and further away for patties of larger size.

The fill passage 26 therefore comprises a supply passage for flow ofmaterial between the pressure chamber space 24 and the receiver chamberspace which is the portion of the cylinder 23 beneath the verticallymovable piston 30. The open bottom end 43 of this cylinder 23 adjacentthe mold plate 27 likewise comprises a flow passage for flow of materialfrom the receiver chamber or cylinder 23 to the mold opening 32.

The mold 27 also includes a barrier portion 44 that is located betweenthe fill passage 26 and the mold opening 32 for blocking the flowpassage 26 in the bottom plate 17 when the mold has moved the moldopening 32 into filling position as shown in FIG. 6.

In the illustrated embodiment the flow passage 43 from the receiverchamber cylinder 23 to the mold opening 32 has a transverse area that isless than that of the mold opening 32. This is particularly advantageouswhen molding food material such as raw ground beef that contains tissueand similar fibers and that requires later cooking. This is an advantagebecause unless this tissue is arranged in other than parallel patternsthe cooking and similar processing tends to cause the molded articlesuch as a circular patty to shrink nonuniformly so that a distortedshaped product is produced. By having the mold opening with a transversearea larger than that of the flow passage 43, however, the tissue isarranged generally radially so that during cooking and resultantshrinking the circular patty maintains its circular though smallershape.

In connection with FIG. 6, it should also be noted that the flow passage43 from the cylinder 23 is of substantially the same transverse area asthe interior of the cylinder 23 so that the material 31 flows smoothlyfrom beneath the piston 30 into the mold opening. This is a particularadvantage in the molding of a food material such as ground raw beef asit avoids excessive working of the material which tends to squeeze outthe juices and toughen the cooked food material so that there is notonly deterioration in texture causing the meat to be tougher but also agreat reduction in flavor because of the expelling of the juices.

In fact, this invention is particularly adaptable to molding such foodmaterial as ground raw beef because it does avoid excessive working ofthe material which tends to expel the juices and toughen the product andreduce its flavor and it also avoids aligning any tissues in parallelpatterns which, as noted above, causes uneven shrinkage during cooking.

When the piston 30 has been moved downwardly to the lowered positionshown in FIG. 6 to fill the mold opening 32 and produce the resultingpatty 41 the bottom surface 45 of the piston 30 is substantially flushwith the top surface 46 of the mold plate 27.

The bottom part 47 of the apparatus 10 is provided with the motor drivefor the apparatus. This comprises an electric motor 50 that drives agear reducer 51 through a shaft coupler 52. Extending from the oppositesides of the reducer 51 are aligned power shafts 53 of which only one isshown in the drawings but with the shaft on the opposite side beingexactly the same. Each of these oppositely located shafts 53 drives alever system that includes a short link 54 rotatable in a clockwisedirection 55 as viewed in FIG. 6, with this link being rotatablyconnected to one end of a second link 56 whose opposite end is rotatablyconnected to about the midpoint of a third link 57. The lower end ofthis third link 57 is fulcrumed on a mounting bracket 60 while the upperend of this third link 57 is hingedly connected to a fourth link 61whose other end is hingedly connected to a slide block 62.

As noted above, although only one set of linkages and slide block areshown on the one side of the apparatus illustrated, there is acorresponding set on the opposite side of the apparatus.

The mold plate 27 slides between the previously described plate 17 and abottom plate 63 which is supported by a plate 64. Mounted on this plate64 at each end of the apparatus is a slide bracket 65 and 66 withanother pair of exactly similar brackets provided on the opposite sideof the apparatus. Each pair of brackets 65 and 66 slidably supports adrive rod 67. There are thus provided two of these drive rods 67 inparallel arrangement on opposite sides of the apparatus. The rear endportions 70 of the rods have extending between them a transverse drivebracket 71 and mounted on the forward end 72 of each slide rod 67 is amold plate drive block 73 that is connected to the forward end of themold plate by an upwardly projecting pin 74 on each side of the moldplate.

Each slide block 62 slides on its drive rod 67 in a path that is definedby a pair of spaced drive collars 75. These collars provide a lostmotion connection between the slide blocks 62 and the drive rods 67.Thus when each block 62 is against the forwardmost collar 75 as shown inFIG. 6 and the shafts 53 are rotating as indicated at 55 the rods 67 aremoved forwardly as shown by the arrow 76 in FIG. 6. However, when therotation of the gear reducer shafts 63 and the linkage systems connectedthereto moves the slide blocks 62 rearwardly as indicated by the arrow77 in FIG. 4 the slide blocks 67 and the portions of the structureattached thereto do not begin their rearward movement until the slideblocks 62 reach the rear drive collars 75.

The drive bracket 71 in its reciprocating movement between the extremepositions of FIGS. 6 and 4 drives a sleeve 80 that extends through therear wall 22 of the pressure chamber 16 to engage a threaded nut 81 thatis spaced a short distance rearwardly of the ram 20. This nut 81 engagesthe threaded forward end 82 of a shaft 83 that is located within thesleeve 80. This shaft 83 is rotatable by turning a head 84 attachedthereto rearwardly of the drive bracket 71.

Concentrically around and spaced from the sleeve 80 is a horizontalcylinder 85 that is slidable in the rear wall 22 and this cylinder atits forward end surrounds the threaded nut 81. Fastened to the interiorof the cylinder 85 and spaced from the nut 81 is an annular collar 86.Positioned between this collar 86 and the nut 81 is a helical spring 87that is located in a space between the sleeve 80 and the cylinder 85.The nut 81 is slidable within the forward end of the cylinder 85 andbecause it is fastened to the sleeve 80 which is itself fastened to thehead 84, turning the shaft 83 adjusts the position of the nut 81longitudinally and thus adjusts the precompression of the helical spring87. The forward end of the shaft 83 is attached to the ram 20 by a crosspin 90.

The head or handle 84 may thus be used to adjust the compression on thespring 87. If the handle 84 is turned in a clockwise direction as viewedfrom the rear it draws the nut 81 toward it on the threaded forward end82 of the shaft 83 which nut 81 is slidable on the interior surface ofthe cylinder 85. Conversely, rotating the head 84 in a counterclockwisedirection moves the nut 81 further away and reduces the compressiveforce on the spring 87. In making these adjustments the handle or head84 rotates freely on the shaft 83. The precompression thusly applied tothe spring 87 presses the end collar 86 firmly against the drive bracketyoke 71 as the collar 86 is pinned securely to the cylinder 85 by threescrew pins as illustrated.

In order to feed material from the hopper 11 into the pressure chamber16 there are provided a pair of cylindrical feeders 91 and 92 eachprovided with spaced pins 93 sloped in the directions of rotation asshown by the arrows 94. These feeders 91 and 92 are mounted on crossparallel shafts 95 above and on opposite sides of the opening 14 intothe pressure chamber 16 and when the feeders are rotated the pins whichmove from the top toward each other project a vertical column ofmaterial through the opening 14 to provide the depending amount 15 ofmaterial. In order to prevent the material being carried around by therotating pins 93 there are provided combs 98 on opposite sides of theslot exit opening 14 with each comb comprising teeth spaced apartslightly greater than the width of a pin 93 so that the passage of thepins through the combs 98 will tend to strip material carried by thepins.

The feeders 91 and 92 are provided with intermeshing circular gears 96concentric with the shafts 95 with these gears being concealed behind afront wall 97. These gears rotate the feeders in the directions 94intermittently with each reciprocation of the drive rods 67. Thisintermittent rotation is accomplished in the following manner.

One of the pair of parallel shafts 95 has mounted thereon a one-wayclutch 101 having a projecting arm 102. This clutch permits rotation ofthe shaft 95 to which it is attached only in a clockwise direction asviewed in FIG. 3. Because of the meshing of the gears 96 this of coursecauses rotation of the opposite shaft 95 only in a counterclockwisedirection.

Attached to the outer end of the clutch arm 102 is a depending verticaldrive member 103 whose lower end 109 carries a stub shaft 104 whichprojects inwardly to engage an elongated slot 105 in a cam plate 106.

This cam plate is of generally bifurcated construction with one end 107of a branch 110 hingedly connected to the bottom portion 47 of theapparatus and the other branch 111 providing an inclined cam surface112. As can be seen from FIGS. 1 and 3 the slot 105 in which is locatedthe stub shaft 104 is positioned adjacent to the area of joining of theangular branches 110 and 111.

A helical spring 113 is provided having an upper end attached to theframe of the apparatus and a lower end attached to an end portion 114 ofthe vertical drive member 103 in order to constantly urge the drivemember and thus the clutch arm 102 and cam 103 in an upward direction.

In order to apply pressure to the cam surface 112 and urge it and thusthe drive member 103 and clutch arm 102 downwardly a slide block 62carries a depending cam follower roller 114. When the mold plate and themold plate drive are in the forwardly projected position as shown inFIG. 1 the slide blocks 62 and the roller 14 are likewise in theirforwardmost positions. Then movement of the slide blocks 62 toward theirrearwardmost position of FIG. 3 carries the cam follower roller 114rearwardly to engage the inclined cam surface 112 and depress the camplate 106 downwardly about its hinge 116 connection to the bottom part47 of the frame of the apparatus as shown in FIG. 3.

This arrangement of the cam roller 114 causes the counterclockwisearcuate movement of the cam plate 106 to pull the drive member 103downwardly as indicated at 116 thereby turning the clutch 101 clockwiseand because of the intermeshing gears 96 turning the feeders toward eachother as shown by the arrows 117 in FIG. 3. This indexes the feeder pinstoward the opening 14 between the hopper 11 and the pressure chamber 16to project the material 15 into the pressure chamber. Then, when theforward movement of the drive mechanism and the mold plate begins theforward movement of the slide blocks 62 carries the cam follower roller114 forwardly to release the cam 106 thereby permitting the spring 113to raise the cam 106 to its elevated position of FIG. 1 and to returnthe clutch arm 102 to its elevated position against an adjustable stop120. The adjustable stop 120 which as shown in this embodiment is anelongated screw threadably engaging a bracket 121 adjusts the upwardposition of the clutch arm 102. This upper or retracted position of theclutch arm 102 and thereby the clutch 101 predetermines the amount 15 ofmaterial projected into the pressure chamber 16. Obviously, the higherthe position of the clutch arm 102 the greater the arcs of movement ofthe feeders 91 and 92 and the greater the volume of material 14 that ismoved into the pressure chamber.

In reciprocating the ram 20 rearwardly from the forward position of FIG.4 toward the retracted position of FIG. 6 it sometimes occurs that thesuction of the retracting ram pulls the portion 122 of material at thefront surface 123 of the ram rearwardly with the ram. In order toprevent this a vacuum release venting means is provided. This releasemeans comprises a plurality, here shown as four, of holes 124 throughthe front wall 21 of the pressure chamber 16 and a normally open flatvalve plate 125 encompassing these holes. The plate 125 is within thespace 24 at the forward end of the pressure chamber and the plate isheld in the normally open position of FIG. 6 by a leaf spring 126. Withthis arrangement the leaf spring 126 normally holds the valve plate 125spaced from the opening 124. However, the advancing material pressedforwardly by the ram 20 engages and closes this valve plate so that thepressurized charge of material cannot escape through the opening. Thenwhen the ram moves to the rear or from the position of FIG. 4 to theposition of FIG. 6 suction developed at the front face of the ram opensthe valve to permit air to enter and relieve this suction.

The pair of short or first links 54 which are rotatable with theoppositely projecting drive shafts 53 carries on their outer ends at thehinge connection to the two links 56 a crescent cam 127. Each cam 127has an arcuate cam surface 130 that at its forward end with relation tothe direction of rotation 55 and for most of the extent of the surface130 is concentric with the axis of rotation of the shaft 53. Thisforward portion 131 of the cam surface arcuately curves toward the axisof rotation at its rear portion 132 as shown most clearly in FIGS. 3 and6.

These cam surfaces 130 each engage a roller 133 that acts as a camfollower with each roller being mounted on a generally horizontal drivebar 134. Each drive bar has a rear end fulcrumed to a mounting bracket135 and its forward end hingedly connected to the bottom of a verticaldrive bar 136. The two drive bars are vertical and substantiallyparallel to each other and carry at their upper ends above the cylinder23 a cross bar 137. The cross bar 137 has a central opening 140 intowhich extends the upper end of the piston 30 stem 33. Located above thisopening 140 is an enclosing bracket 141 in which is located a verticallymovable stub shaft 142 that is urged downwardly to press a collar 143against the top of the cross bar 137 by a helical compression spring144. This spring 144 and associated structure limits the amount ofdownward force that can be exerted on the material 31 within thecylinder 23 by the descending piston 30.

When the apparatus is properly adjusted the ram 20 is moved forwardly toproject the amount of pressurized material 31 beneath the piston 30 toexactly fill the mold opening 32. If, however, through maladjustment toomuch material is transferred to the pressure chamber 16, as indicatedfor example at 15, the upward movement of the piston 30 being stopped bythe stop 36 at that amount necessary to fill the mold opening means thatthe excess will gradually accumulate in front of the front surface 123of the pressure ram. This accumulation 122 gradually builds up becausethe amount of material that can enter beneath the piston 30 is limitedby the collar 34 and stop 36. When the accumulation reaches a certainamount, the pressure ram 20 is held rearwardly from its position in FIG.4 to expose an upwardly extending vent slot 145 leading from thisportion of the pressure chamber up to the interior of the hopper 11rearwardly of the adjacent comb 98. Because this passage 145 is so shorteven when the apparatus is thus maladjusted the forcing of the excessmaterial back into the hopper is this manner does not excessively workand does not toughen the meat. On the opposite end of the pressurechamber 16 there is provided a second vent slot 146 that provides areturn passage for material that leaks to the rear of the ram. Thismaterial is compressed by the rear face 147 of the ram 20 and forced upthe slot 146 again to a portion of the hopper that is rearwardly of theadjacent comb 98. This slot 146 like the first slot 145 returns thematerial without excess working which in the case of meat is importantin order to prevent toughening of the meat and reducing its flavor forthe reasons previously described.

When the mold plate 27 is in its forwardmost position in the embodimentillustrated the formed patty 41 is removed from the opening by aknockout mechanism that includes a vertically movable cup 150 that isreciprocated in a vertical direction as shown by the arrow 151 into andout of the mold opening 52 during the pause in the movement of the moldplate due to the lost motion connection provided by the spacing of thedrive collars 75 on opposite sides of each slide block 62. The knockoutmechanism including the cup 150 and apparatus for moving it in avertical direction 151 may be any of these customarily used and widelyknown. Examples of such knockout or patty removing apparatus are shownand described in U.S. Pat. Nos. 3,293,688 and 3,417,425, both assignedto the assignee hereof.

The operation of the apparatus in the disclosed embodiment is believedobvious from the above description. However, a brief summary of theoperation is as follows.

The motor or gear reducer rotate the opposite drive shafts 53 in thedirection indicated to reciprocate the slide blocks 62 on their driverods 67. This reciprocates the mold plate 27 between the rearwardmostposition of FIGS. 3 and 6 and the forwardmost position of FIGS. 1 and 4.When the mold plate and the drive mechanism which drives it are in theirforwardmost positions as shown in FIGS. 1 and 4 the knockout structure150 is reciprocated vertically 152 into and out of the mold plateopening 32 to remove the patty 41 therefrom.

Because the drive rods 70 and drive bracket 71 interconnect the moldplate 27 and the ram 20 these move simultaneously in the same direction.Because of the location of the fill passage 26 in the mold plate whenthe mold opening 32 is in position for removal of the patty 41 asdescribed the fill passage 26 interconnects the bottom of the pressurechamber fill slot 25 and the bottom end 43 of the cylinder 23. Thiscauses the ram 20 to force the pressurized material 31 through the slot25 and up into the cylinder to raise the piston 30 to the point wherethe collar 35 engages the stop 36. This predetermines the amount ofpressurized material 31 beneath the piston and when the apparatus isproperly adjusted this amount will be exactly that required to fill themold opening 32 to produce the shaped patty 41.

Then rearward movement 77 of the drive portions of the apparatus causethe slide blocks 62 to engage the rear drive collar 75 when the knockoutcup 150 has been raised from the mold opening 32. Continued rearwardmovement of the slide blocks 62 retracts the ram 20 to the positionshown in FIG. 6 and in this completely retracted position and the moldopening 32 is directly and concentrically beneath the cylinder 23. Therotation 55 of the links 54 causes the cam surface forward portion 131to engage the cam follower roller 133 on each side of the apparatus andpull the piston 30 down sharply to the position where the bottom surface45 is flush with the top surface 46 of the mold plate. Because of thecoaxial relationship of the leading cam surface 131 of the cam 127 thepiston is held in this position until the forward movement 76 of thelinkage system causes the slide blocks 62 engaging the forward drivecollar 75 to again move the ram and mold plate to the position shown inFIG. 4.

During the time that the piston 30 is being depressed to the positionshown in FIG. 6 to fill the mold opening 32 the barrier portion 44 ofthe mold plate is beneath the slot 25 leading from the forward end ofthe pressure chamber so that no more material can flow therethroughwhile the mold opening is being filled.

The continued rotation of the cam 127 permits release of the downwardpressure on the piston 30 but this is only after the mold opening 32 hasbeen moved out of position beneath the cylinder 23

As previously stated, the incoming pressurized charge 31 of materialraises the piston 30 to its uppermost position as shown in FIG. 4. Atthe same time the tension of the spring 113 pulls the drive member 103and the cam plate 106 to their elevated positions shown in FIG. 1 withthe clutch bar 102 against the stop 120. This upward movement of theseparts of the apparatus does not cause any movement of the feeders 91 and92 because of the provision of the one-way clutch 101.

Then rearward movement 77 of the slide block 62 and correspondingrearward movement of the cam follower roller 114 causes the engagementof the follower with the cam edge 112 to depress the cam plate 106 andindex the feeders downwardly arcuately as indicated by the arrows 117 toprovide a fresh charge of moldable material in the pressure chamber 16.

In the operation of the machine the amount of moldable material 12 suchas ground beef to form the molded article such as the beef patty 41 iseasily predetermined by adjusting the position of the stop 120 whichdetermines the upward position of the clutch arm 102. This in turndetermines the amount of material that will be captured by the feederpins 83 so that the cam 106 operated feeder drive member 103 willproject the exact amount of material into the compression chamber 16 forforming one molded article or patty 41 when the piston 30 has beenpulled down as described to its lowermost position of FIG. 6 wherein itsbottom 45 is flush with the top of the mold plate 27. This relationshipis illustrated in both FIGS. 6 and 7.

The amount of material 15 necessary to form the molded article 41 is notimmediately pressed into the cylinder 23 to provide the portion 31 shownin FIG. 4 which is the exact amount of the portion 15 and the exactamount in the patty 41 but, first, the projected amount 15 is forcedforwardly in the compression chamber by the advancing ram 20 as itreaches the position shown in FIG. 4 and this amount is then moved intothe rear end fill passage 26 where it displaces an equal amount ofmaterial upwardly to form the portion 31 beneath the piston 30 which inthis embodiment is raised to this elevated position by the pressure ofthe incoming material 31. Thus with each reciprocation of the ram 20forwardly to feeding position the amount of material required to producethe article 41 is forced into the fill slot and eventually up into thearea beneath the ram 30 in successive portions.

If the apparatus is maladjusted any excess amount over that required toproduce a patty 41 is automatically compensated for because this excessamount on successive strokes of the ram 20 builds up to the point wherethe ram is held retracted by the excess material to where the bypassslot 145 is exposed and the excess begins to be returned to the hopper11 in the manner previously described. If the maladjustment provides toosmall an amount of material to produce the patty 41, it is immediatelyevident in the fact that unfilled patties will begin to be produced bythe apparatus. This will immediately alert the operator to thiscondition and he can make the proper adjustments as by adjusting theposition of the stop 120 until the condition is corrected. If heoveradjusts so that too much material is fed into the compressionchamber 16 for making a patty 41, this excess will be returned to thehopper through the passage 145 in the manner previously described.

The opposite vent slot 146 merely takes care of leakage around the ramso that close tolerances of the ram and selfadjusting seals are notrequired.

As is evident from the disclosure the molding apparatus of thisinvention can be used to mold any type of pressure moldable materialthat is self-sustaining once it has been molded. However, it isparticularly adapted for making molded articles such as patties of foodmaterials such as raw meat. The apparatus is particularly adapted forfood material molding because it avoids shearing which tends to alignany tissue in parallel so that during cooking the article such as thehamburger patties shrink out of round. Shearing is avoided by having thebottom 45 of the feed piston 30 substantially flush with the top 46 ofthe mold plate 27 as shown in FIGS. 6 and 7 so that there is no movementof one portion of meat relative to an adjacent portion as when the moldplate is moved to the patty ejecting position of FIG. 1. Similarlybecause the fill opening 14 is long and narrow the forward moving ram 20which cuts off the depending portion 15 of material necessary to form apatty 41 is sheared but the area involved is so small that it has nomaterial effect on the alignment of the tissue. Similarly, any alignedtissue that might prevail is immediately corrected by the forcing of thetissue containing meat first downwardly in the slot 25 as shown in FIG.4 and then forwardly in the passage 26 and then upwardly beneath the ram30.

The forcing of the tissue containing food material forwardly in the fillpassage 26 also tends to cause an alignment of the tissue in parallel asit flows forwardly in the passage 26 and up into the space beneath theelevated ram 30. However, when the food material contains such tissue itis preferred that the diameter of the mold opening 32 be greater thanthe diameter of the open bottom flow passage 43 so that the descendingpiston 30 when forced from the raised position of FIG. 4 to the loweredposition of FIG. 6 causes the tissue containing food material to firstpass longitudinally downwardly and then radially outwardly to theperiphery of the mold opening 32 and this combined longitudinally andradial movement destroys any parallel alignment of the tissues so thatthe resulting patty or similar article will shrink uniformly.

When used on food material such as meat which contains a mixture offluids and solid particles the high quality of the material ismaintained because the pressures employed by the apparatus of thisinvention are gentle so that the juices are not squeezed from thetissues and the resulting shaped articles such as patties are similar intexture and flavor to those shaped by the gentle pressure of handmolding.

Another feature that contributes to the high quality of the shapedarticle that is particularly important when the material is food is thefact that no air is trapped in the space beneath the piston 30 in thecylinder 23. This is true because the entire space between the forwardlypressed ram 20 as illustrated in FIG. 4 and the surface 45 of the piston30 is completely filled with material at all times.

Having described my invention as related to the embodiment shown in theaccompanying drawings, it is my intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but rather be construed broadly within its spirit and scopeas set out in the appended claims.

I claim:
 1. Apparatus for pressure molding a shaped article from atissue containing food material subject to shrinkage during cooking,comprising: supply means for said material; a pressure chambercommunicating with said supply means to receive material therefrom; amovable pressure applying means in the pressure chamber; a receiverchamber; means providing a supply passage for flow of material betweensaid pressure chamber and said receiver chamber communicating with saidpressure chamber to receive pressurized material from said pressurechamber; means for moving said pressure applying means in said pressurechamber for exerting pressure on said material and thereby forcing theresulting said pressurized material into said receiver chamber; amovable mold plate having a cavity mold opening for registering with thesaid material in said receiver chamber; means for moving said moldopening into communication with said receiver chamber; means providingfor flow of material from said receiver chamber to said mold opening; apiston in said receiver chamber; means for positioning said piston awayfrom said mold plate to provide space for a preselected amount of saidmaterial between said piston and said mold plate opening; mold fillingmeans for forcibly moving said piston to apply pressure to the saidmaterial in said receiver chamber thereby filling said mold opening withsaid material, said piston having a pressure applying end that issubstantially flush with said mold plate at the completion of saidfilling; means for thereafter moving said mold and thereby said moldopening to a position where said mold opening is out of communicationwith said receiver chamber whereat said article is ejected from saidmold opening; and means for maintaining said piston substantially flushwith said mold at said opening during said moving of said mold openingthereby maintaining molding pressure on said material in said opening.2. The apparatus of claim 1 wherein said supply passage comprises aportion of said mold plate.
 3. The apparatus of claim 2 wherein saidmold plate comprises a barrier portion for periodically blocking saidflow passage of said receiver chamber.
 4. Apparatus for pressure moldinga shaped article from a tissue containing food material subject toshrinkage during cooking, comprising: supply means for said material; apressure chamber communicating with said supply means to receivematerial therefrom; a cylinder having an open end; a piston in saidcylinder movable toward and away from said open end; a mold having amold opening for registering with said open end to receive materialtherefrom; means for moving said mold and thereby the mold opening to aposition where said mold opening is out of communication with saidcylinder whereat said article is ejected from said mold opening; meansfor transferring material from said pressure chamber into said cylinderin one position of said mold; means for moving said piston toward themold in a second position of said mold to project material from saidcylinder into said mold opening; and cam means for both moving saidpiston toward said mold opening and then maintaining said pistonsubstantially flush with said mold at said opening during said moving ofsaid mold opening thereby maintaining molding pressure on said materialin said opening.
 5. The apparatus of claim 4 wherein there are providedadjustable stop means for limiting the extent of movement of said pistonto define with said cylinder a material receiving space and predeterminethe volume of material transferred into said space, the volume of saidmaterial receiving space being substantially equal to the volume of saidmold opening.